Battery for powering a medical device having low magnetic susceptibility

ABSTRACT

A laryngoscope constructed of materials including metal components having very low magnetic susceptibilities is described. The battery powering the laryngoscope lamp is a lithium battery also constructed of materials having low magnetic susceptibilities. The battery further includes a unique terminal configuration that prevents the inadvertent use of other batteries, including non-magnetic batteries, in the laryngoscope. A unique lamp retaining mechanism provides for quick and easy replacement of the lamp.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 08/837,339,filed Apr. 11, 1997, now U.S. Pat. No. 6,036,639.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a hand held medical device.More particularly, the present invention relates to a laryngoscope, andstill more particularly to a laryngoscope that is constructed ofmaterials having relatively low magnetic susceptibilities. This providesthe laryngoscope of the present invention as a useful instrument in thevicinity of a magnetic resonance scanner.

2. Prior Art

Laryngoscopes generally comprise a detachable blade and a cooperatinghandle which are connected together in an L-shaped configuration. Thehandle serves as an enclosure for one or more batteries which energize alight source in the handle. The switch for energizing the light sourceis usually positioned at the top of the handle immediately adjacent tothe light source and is activated by the blade when it is connected tothe handle and moved into an operative position. Light from the lightsource is directed to the light conductor disposed in or on the blade.Light passes through the light conductor to the distal end thereof toilluminate the field of view such as a patient's mouth and larynx duringthe examination thereof by medical personnel and during the insertion ofan endotracheal tube into the trachea of the lungs to administeranesthetic gases therein.

The prior art is replete with various types of metallic laryngoscopes,some of which are capable of illumination. Additionally, U.S. Pat. No.4,607,623 to Bauman describes a laryngoscope constructed of non-ferrousmaterials such as ABS with the electrically conductive portions providedby first applying a thin copper layer to the ABS followed by electrolessplating and then electrolytically plating another copper layer to form aconductive layer about 0.5 to 2 mils thick. A thin layer of aluminum issubsequentially applied to the copper coating in those areas intended tobe reflective. The batteries powering this device are not furtherdescribed, but may be of a nickel/cadmium type commonly used for suchapplication. Nickel/cadmium batteries are not considered to berelatively nonmagnetic and would not be useful with the laryngoscope ofthe present invention.

U.S. Pat. Nos. 310,004 to Weston; 485,089 to Carhart; 2,282,979 toMurphy; 3,352,715 to Zaromb; 3,673,000 to Ruetschi and 4,318,967 toRuetschi disclose anti- or non-magnetic materials in cells or batteries.Additionally, U.S. Pat. Nos. 2,864,880 to Kaye; 2,982,807 to Dassow etal.; 4,053,687 to Coiboin et al.; 4,264,688 to Catanzarite; 4,595,641 toGiutino; 5,104,752 to Baughman et al.; 5,149,598 to Sunshine; 5,173,371to Huhndorff et al.; 5,194,340 Kasako; 5,418,087 to Klein; and 5,443,924to Spellman relate to batteries having means for assuring that properbattery polarity is established. However, none of these patents describepower sources that are useful with the hand held medical device of thepresent invention because they either include at least some magneticcomponents, do not have sufficient energy density for extended use or donot have a terminal configuration similar to that of the presentinvention. U.S. Pat. No. 4,613,926 to Heitman et al. discloses anilluminating assembly for an MRI scanner.

There is needed a lighted laryngoscope that is predominantly constructedof metal so that the instrument is capable of withstanding the abusivetreatment conditions which surgical instruments are sometimes subjectedto. For this purpose, the laryngoscope of the present invention isconstructed largely of metal components. However, with ever increasinguse of magnetic resonance scanning to aid medical personnel during pre-and post-clinical and surgical procedures, the metal components must beconstructed of materials that have as low a magnetic susceptibility aspossible.

SUMMARY OF THE INVENTION

The laryngoscope of the present invention is constructed of materialsincluding metal components having very low magnetic susceptibilities.Those parts not made of metal are preferably formed of a thermoplasticmaterial, for example an acetal compound such as DELRIN. The batterypowering the laryngoscope lamp is also constructed of materials havinglow magnetic susceptibility. Lithium batteries are preferred, and allcomponents such as the casing, terminal leads, current collectors andcollector leads, some of which are typically made of nickel, areconstructed of stainless steel nonmagnetic austenitic. The batteryfurther includes a unique terminal configuration that prevents theinadvertent use of other batteries, including non-magnetic batteries, inthe laryngoscope. A unique lamp retaining mechanism provides for quickand easy replacement of the lamp.

These and other aspects of the present invention will become moreapparent to those skilled in the art by reference to the followingdescription and to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a laryngoscope 10 according to thepresent invention.

FIG. 2 is an exploded view of the laryngoscope handle 12 and headassembly.

FIG. 3A is a partial, cross-sectional view of a portion of the handle 12and the head assembly for the laryngoscope 10.

FIG. 3B is a partial, cross-sectional view of the handle 12 and end cap50 for the laryngoscope 10.

FIG. 4 is a plan view of the battery 32 for the laryngoscope 10.

FIG. 5 is a side, elevational view of the battery 32.

FIG. 6 is a perspective view of the head 100 for the laryngoscope 10.

FIG. 7 is a perspective, exploded view of the lamp retainer 124 for thelaryngoscope 10.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings, FIGS. 1 to 7 show a laryngoscope 10 havinglow magnetic susceptibility characteristics according to the presentinvention and generally comprised of a handle 12, a detachable blade 14and an attachment means 16 for detachably securing the blade 14 to thehandle 12 in a generally L-shaped configuration. The instrument isutilized to depress a patient's larynx during an examination thereof orduring the insertion of an endotracheal tube. The blade is of stainlesssteel or a fiberglass composite commercially available from Heine underthe trademark SANALON.

With particular reference to FIGS. 2, 3A, and 3B, the handle 12 is acylindrically-shaped tube comprising an intermediate section 18 meetingat a step 20 with a proximal section 22 having internal threads 24, andthe intermediate section 18 meeting at a chamfer 26 with a distalsection 28. The outer surface of the handle 12 is provided with raised,knurled ridges 30 (FIG. 1) to aid in gripping the laryngoscope 10. Thehandle 12 is preferably constructed of chrome plated brass.

A battery 32 (FIGS. 2, 3A, 3B, 4 and 5) is housed inside theintermediate handle section 18 for providing power to a lamp means as anassembly 34, which will be described in detail hereinafter. The battery32 is constructed of materials having relatively low magneticsusceptibility with a unique terminal configuration according to thepresent invention. The battery 32 is preferably an alkali metal batteryand more preferably an alkali metal/liquid catholyte battery. A mostpreferred chemistry utilizes the lithium/thionyl chloride-brominechloride (Li/BCX) couple. The battery casing adjacent to the distalhandle section 28 is insulated to prevent electrical contact in theconventional manner.

As shown in FIGS. 3A, 4 and 5, the opposite end of the battery 32includes a negative contact ring 36 that is permanently attached to thebattery case to provide one terminal for the battery. The central,positive terminal 38 is recessed and insulated by material 40 around itsperimeter to prevent accidental shortening. A non-magnetic fuse 42prevents inadvertent run-away electrochemical reaction while athermoplastic insulator plate 44 supported on a ledge of the insulatedmaterial 40 protects the positive terminal 38 and fuse 42. A centralopening 46 in plate 44 provides for access to the positive terminal 38.To provide the battery 32 having a relatively low magneticsusceptibility, all external and internal electrical components such asthe casing, the terminals 36,38, the current collectors and the contactleads are of stainless steel.

The unique terminal configuration prevents the inadvertent loading anddischarge of batteries into the handle 12 not intended for use with thelaryngoscope 10. Such inadvertent battery use could have detrimentalaffects on the laryngoscope's low magnetic susceptibilitycharacteristics.

The battery 32 is secured inside the handle 12 by a cap spring 48,preferably of silver plated beryllium copper, that biases between thebattery and an end cap 50 snug-fitted into the distal handle section 28extending part way into the intermediate handle section 18. The end cap50 is of a non-magnetic material, such as an acetal thermoplasticmaterial with an enlarged head 52 that abuts the distal end of handle12. A groove 54 formed between the cap head 52 and an annular protrusion56 of the cap receives an O-ring 58 of a flexible elastomeric materialfor sealing the cap 50 in the distal section 28 of the handle 12 in afluid tight engagement.

As shown in FIGS. 2 and 3A, a battery retainer assembly is threaded intothe proximal handle section 22 and includes a battery retainer 60,preferably of an acetal thermoplastic material, that threads into thehandle 12 to capture a battery pin 62, a battery spring 64, a tube disk66 and a pair of spring contacts 68 therein. The battery pin 62 ispreferably of gold plated brass, the battery spring 64 is preferably ofsilver plated beryllium copper, the tube disk 66 is of an acetalthermoplastic material and the spring contacts 68 are of silver platedberyllium copper.

The battery retainer 60 comprises a threaded portion 70 sized tothreadingly mate with the internal threads 24 of the proximal handlesection 22. The threaded portion 70 of the battery retainer 60 meets acylindrically-shaped portion 72 that extends to a chamfer 74 ending atan end face 76. The battery retainer 60 has a first,cylindrically-shaped bore 78 that meets at an internal shoulder 80 witha second, lesser diameter cylindrically-shaped bore 82 extending to theend face 76. A pair of diametrically opposed openings 84 are providedthrough the thickness of the threaded portion 70. The battery retainer60 receives the battery pin 62 having a cylindrically-shaped body 86provided with an annular protrusion 88 adjacent to a proximal end 90thereof.

The internal threads 24 at the proximal handle section 22 terminate atan internal shoulder 92. Shoulder 92 supports the tube disk 66 having acentral opening 94. The tube disk 66 also includes a pair of opposedchannels 96 (shown in dashed lines in FIG. 2) that communicate betweenthe outer edge thereof and diametrically opposed portions of the opening94. The tube disk 66 supports the pair of spring contacts 68, eachhaving a leg disposed in one of the disk channels 96 with a contactportion 98 of the springs extending from the opposite face of the tubedisk 66.

As shown in FIG. 3A, with the tube disk 66 supported on the internalshoulder 92, the spring contacts 68 are captured between the shoulder 92and the disk 66 with the contact portions 98 contacting the annular,negative terminal 36 of battery 32. The tube disk 66 and spring contacts68 are secured in this position by the battery retainer 60 threaded intothe proximal handle section 22. The battery retainer 60 further capturesthe battery pin 62 between itself and the tube disk 66 with the proximalend side of the annular protrusion 88 abutted against the internalshoulder 80 of the battery retainer by the battery spring 64 surroundingthe body 86 of the battery pin 62 and biasing between the tube disk 66and the opposite side of the annular protrusion 88. The pair ofdiametrically opposed openings 84 in the battery retainer 60 areprovided to receive a tool (not shown) such as a spanner wrench fortightening the battery retainer 60, battery pin 62, battery spring 64,tube disk 66 and spring contacts 68 into position. The battery retainerassembly together with the battery 32 loaded into the handle 12 andsecured therein by the cap spring 48 and end cap 50 form the portion ofthe laryngoscope 10 of the present invention generally referred to asthe battery pack assembly.

After the battery retainer assembly is threaded into the proximal handlesection 22, the proximal section 22 threadingly receives a head 100. Asshown in FIGS. 2, 3A, 4 and 6, the head 100 includes a cap portion 102having external threads 104 that threadingly mate with the internalthreads 24 at the proximal handle section 22, and the attachment means16 for attaching the blade 14 to the handle 12. The head 100 ispreferably constructed of chrome plated brass.

The head 100 further comprises an internal passage 106 extending fromits threaded end through the cap portion 102 to the attachment means 16.At the threaded end, the bore 106 has a beveled portion 108 taperinginwardly toward a first cylindrical portion 110 that meets with aninternally threaded portion 112 at step 114. The internal threadedportion 112 of head 100 meets with a second cylindrical portion 116 atstep 118 which extends to a shoulder 120 that meets with an opening 122(shown in dashed lines in FIG. 1) leading into the blade attachmentmeans 16.

To provide illumination to a fiber optic blade light conductor 123(shown in dashed lines in FIG. 1), the lamp assembly 34 is mounted inthe internal bore 106 of head 100. The lamp assembly 34 includes a lampretainer 124 (FIGS. 2, 3A and 7) having an interior cylindrically-shapedbore 126 extending to a shoulder 128 that meets with an outwardlybeveled, reflector portion 130. The lamp retainer 124 is preferablyconstructed of stainless steel. A lamp 132 is received inside the bore126 with the lamp casing 134 abutted against the shoulder 128 so thatthe lamp 132 is disposed in a reflective relationship with the reflectorportion 130 of lamp retainer 124. A lamp 132 useful with thelaryngoscope 10 of the present invention is commercially available fromBoehm under model no. X02.88.044.

Lamp retainer 124 is provided with an annular enlarged portion 136opposite a portion of the interior cylindrically-shaped bore 126 andadjacent to shoulder 128. An annular groove 138 in the enlarged portion136 intersects an opening 140 communicating with the interior bore 126.A stainless steel detent in the shape of a ball 142 serving as a lampholder is disposed inside the opening 140. Opening 140 is somewhat lessin diameter than that of the detent 142 so that a portion of the detentprotrudes into the bore 126 contacting the lamp casing 134 of lamp 132received inside the bore 126. The detent 142 is retained in thisposition by a beryllium copper spring clip 144 seated in groove 146 inthe annular enlarged portion 136 to thereby removably hold or retain thelamp 132 in the lamp retainer 124.

The lamp retainer 124 is itself secured in the internal bore 106 of head100 by a lamp retainer ring 148 having exterior threads 150 thatthreadingly mate with the internal threaded portion 112 of head 100. Thelamp retainer ring 148 is preferably constructed of chrome plated brassand further comprises an internal shoulder 152 meeting with an opening154 that is only somewhat greater in diameter than the outer cylindricalside wall of the lamp retainer 124. With the lamp retainer 124 receivedin the internal bore 106 of head 100, a head spring 156, preferablyconstructed of silver plated beryllium copper and sized to surround theouter side wall of the lamp retainer 124, biases between the annularenlarged portion 136 of lamp retainer 124 and the shoulder portion 152of the lamp retainer ring 148 threaded into the head 100.

The lamp 132 is provided with a contact 158 that extends beyond theretainer ring 148 and into the beveled portion 108 of head 100 with theexternal threads 24 of the cap portion 102 mated to the internal threads24 at the proximal handle section 22. In this position, a shoulder 160intermediate the external threads 104 and an annular step 162 abuts theend of the proximal handle section 22. An elastomeric O-ring 164 isreceived in the steps 162, held tightly between the cap 102 and handle12.

The blade 14 is attached to the handle 12 in a pivotal manner by theattachment means 16 which includes a base portion 166 of blade 14, and apair of opposed side walls 168 and 170 extending from a base plate 172supported on the cap portion 102 of head 100. The side walls 168, 170are provided with respective channels 174, 176 that extend part wayacross the length of the side walls from an end thereof. Each side wall168, 170 further includes an opening 178 opposite the terminal end ofthe channels 174, 176.

The base portion 166 of the blade 14 is sized to be received between theside walls 168, 170 of head 100. The base portion 166 also has a throughbore (not shown) sized to receive a pin 180, preferably constructed ofstainless steel, and a pair of spring biased detents 182 (one shown indashed lines in FIG. 1) that are receivable in the respective channels174, 176.

To fix the blade 14 with respect to the handle 12 in the generallyL-shaped configuration, the base portion 166 of blade 14 is positionedbetween the side walls 168, 170 of head 100 with the through borealigned with the openings 178. The pin 180 is moved through the openings178 and bore to thereby pivotably attach the blade 14 to the handle 12.

FIG. 3A shows that when the head 100 is threaded onto the proximalhandle section 22, the contact 158 of lamp 132 contacts the proximal end90 of the battery pin 62. The opposite, distal end 166 of the batterypin 62 is in a raised position, out of contact with the central,positive terminal 38 of battery 32. The lamp 132 is energized bypivoting the blade 14 with respect to the handle 12 about the pin 180until the spring biased detents 182 seat in the opposed channels 174,176 in side walls 168, 170. This movement serves to releasibly lock theblade 14 in the generally L-shaped configuration with respect to thehandle 12. As the blade 14 is so pivoted, the base portion 166 contactsthe lamp retainer 124, moving it and the lamp 132 towards the battery 32and against the biasing force of head spring 156. The lamp contact 158in turn forces the battery pin 62 towards the battery 32 against thebiasing force of the battery spring 64 until the distal end 166 of thepin 62 contacts the central, positive terminal 38 of battery 32 (asshown in dashed lines in FIG. 3A). The electrical circuit is completedthrough the annular, negative contact ring 36, the spring contacts 68,the handle 12, the head 100, lamp retainer ring 148 and the detent 142contacting the lamp casing 134. With the lamp 132 energized, light isdirected to the blade light conductor 123 which transmits the light tothe end of the blade 14. When the laryngoscope 10 is utilized during amedical examination or during the insertion of an endotracheal tube, theconductor 123 helps to illuminate the zone of interest to thereby aidthe physician.

When the blade 14 is pivoted about pin 180 in the opposite direction tobreak the L-shaped configuration, the head spring 156 biases the lampretainer 124 and lamp 132 away from the battery 32 and the batteryspring 64 biases the battery pin 62 out of contact with the central,positive battery terminal 38.

In addition to serving as a portion of the electrical contact path forenergizing the lamp 132, the lamp assembly 34 including the lampretainer 126, detent 142 and spring clip 144 provide a structure forquickly and easily replacing the lamp 132 should it burn out orotherwise malfunction. To change the lamp 132, the head 100 is unscrewedfrom the proximal handle section 22 and the lamp retainer ring 150 isunthreaded from the head 100. This releases the lamp assembly 34 fromthe head 100 and the lamp 132 is easily moved out of the bore 126 in thelamp retainer 124, releasing from contact with the spring clip 144biased detent 142. A new lamp 132 is then replaced inside the lampretainer 124 and the lamp assembly 34 including spring 156 and lampretainer ring 150 are then re-assembled inside the head 100 and the headis screwed onto the handle 12.

In accordance with the stated low magnetic susceptibilitycharacteristics of the laryngoscope of the present invention, Table 1lists the magnetic susceptibilities of the various materials used toconstruct the laryngoscope along with selected other materials.

TABLE 1 Atomic or Density Molecular Susceptibility Material (g/cc)Weight (× 10⁶) Carbon 2.26 12.011 −218 (polycrystalline graphite) Gold19.32 196.97 −34 Beryllium 1.85 9.012 −24 Silver 10.50 107.87 −24 Carbon(diamond) 3.513 12.011 −21.8 Zinc 7.13 65.39 −15.7 Copper 8.92 63.546−9.63 Water (37° C.) 1.00 18.015 −9.03 Human Soft ˜1.00- — ˜(−11.0 toTissues 1.05 −7.0) Air (NTP) 0.00129 28.97 +0.36 Stainless Steel 8.0 —3520-6700 (nonmagnetic, austenitic) Chromium 7.19 51.996 320

It is known that brass is an alloy of copper and zinc.

In contrast, Table 2 lists the magnetic susceptibilities of variousrelatively highly magnetic materials.

TABLE 2 Atomic or Density Molecular Material (g/cc) WeightSusceptibility Nickel 8.9 58.69    600 Stainless 7.8 — 400-1100 Steel(magnetic, martensitic) Iron 7.874 55.847 200,000

The data use to construct Tables 1 and 2 was obtained from a paperauthored by John Schneck of General Electric Corporate Research andDevelopment Center, Schenectady, N.Y. 12309, entitled “The Role ofMagnetic Susceptibility In Magnetic Resonance Imaging:Magnetic FieldCompatibility of the First and Second Kinds”. The disclosure of thatpaper is incorporated herein by reference.

Thus, the laryngoscope of the present invention is an instrument whichis useful for pre and post clinical and surgical applications,especially in an environment proximate the strong magnetic field emittedby a magnetic resonance scanner.

It is appreciated that various modifications to the inventive conceptsdescribed herein may be apparent to those of ordinary skill in the artwithout departing from the spirit and scope of the present invention asdefined by the appended claims.

What is claimed is:
 1. A battery which comprises: a) a casing comprisinga first end and a second end; b) an anode housed inside the casing; c) acathode housed inside the casing in operative association with theanode; d) a first terminal connected to one of the anode and thecathode; e) a second terminal connected to the other of the anode andthe cathode, wherein the casing has a side wall between opposed firstend and second ends and wherein the second end and at least part of thecasing side wall are provided with an insulative material to preventelectrical contact therewith; and f) wherein the first end of thebattery casing comprises the first terminal as a continuous membersurrounding the second terminal and having a first contact surfacedisposed in a first plane spaced from the second end of the casing,wherein the second terminal comprises a second contact surface disposedin a second plane spaced from the second end of the casing, a firstdistance from the first plane to the second end, the casing beinggreater than a second distance from the second plane to the second endof the casing.
 2. The battery of claim 1 wherein the first, continuousterminal of the battery comprises a planar ring at the first end and thesecond terminal is disposed in a recessed position towards the secondend of the battery with respect to the plane of the ring.
 3. The batteryof claim 1 wherein the battery is an alkali metal battery.
 4. Thebattery of claim 1 wherein the battery is an alkali metal liquid cathodebattery.
 5. The battery of claim 1 wherein the first contact surface isa planar ring supported on the first end of the casing and surroundingthe second terminal.
 6. The battery of claim 1 wherein the batterycomprises a lithium thionyl chloride battery.
 7. The battery of claim 1wherein the battery comprises a lithium bromine chloride battery.
 8. Thebattery of claim 1 wherein the casing sidewall has a cylindrical shapeextending to and meeting with the opposed first end and second end, withthe casing side wall and second end of the casing being of an insulatormaterial and the first end of the casing supporting the first and secondterminals.
 9. The battery of claim 1 wherein the second terminalcomprises a cylindrically-shaped side wall extending to the secondcontact surface.
 10. The battery of claim 1 wherein the second firstplane and second plane are parallel.
 11. A battery which comprises: a) acasing comprising a first end and a second end; b) an anode housedinside the casing; c) a cathode housed inside the casing in operativeassociation with the anode; d) a first terminal connected to one of theanode and the cathode; e) a second terminal connected to the other ofthe anode and the cathode, wherein the casing has a side wall betweenthe opposed first end and the second end and wherein the second end andat least part of the casing side wall are provided with an insulativematerial to prevent electrical contact therewith; f) wherein the firstend of the battery casing comprises the first terminal as a continuousmember surrounding the second terminal and having a first contactsurface disposed in a first plane spaced from the second end of thecasing, wherein the second terminal comprises a second contact surfacedisposed in a second plane spaced from the second end of the casing, afirst distance from the first plane to the second end the casing beinggreater than a second distance from the second plane to the second endof the casing; and g) a fuse proximal to the casing and in operativeassociation with the second terminal, the fuse for preventinguncontrollable chemical reactions.
 12. The battery of claim 11 whereinthe battery is an alkali metal liquid cathode battery.
 13. The batteryof claim 11 wherein the battery comprises a lithium thionyl chloridebattery.
 14. The battery of claim 11 wherein the battery comprises alithium bromine chloride battery.
 15. The battery of claim 11 whereinthe battery casing defines a recess into which the fuse is positioned,and the battery further comprises a protective plate aligned in therecess to cover and protect the fuse from damage.
 16. The battery ofclaim 11 wherein the first contact surface is a planar ring supported onthe first end of the casing.
 17. The battery of claim 11 wherein thefuse is made of non-magnetic materials.
 18. A battery which comprises:a) a casing comprising a first end and a second end; b) an anode housedinside the casing; c) a cathode housed inside the casing in operativeassociation with the anode; d) a first terminal connected to one of theanode and the cathode; e) a second terminal connected to the other ofthe anode and the cathode, wherein the casing has a side wall betweenthe opposed first end and the second end and wherein the second end andat least part of the casing side wall are provided with an insulativematerial to prevent electrical contact therewith; f) wherein the firstend of the battery casing comprises the first terminal as a continuousmember surrounding the second terminal and having a first contactsurface disposed in a first plane spaced from the second end of thecasing, wherein the second terminal comprises a second contact surfacedisposed in a second plane spaced from the second end of the casing, afirst distance from the first plane to the second end the casing beinggreater than a second distance from the second plane to the second endof the casing; g) wherein the first contact surface is a planar ringsupported on the first end of the casing, and the first end defines arecess in which the second terminal is located; and h) a fuse supportedon the casing and in the recess and in operative association with thesecond terminal, the fuse for preventing uncontrollable chemicalreactions.
 19. The battery of claim 18 wherein the battery furthercomprises a protective plate aligned in the recess to cover and protectthe fuse and the second terminal from damage.
 20. The battery of claim19 wherein the protective plate is disposed in a third plane, the thirdplane intermediate the first plane and the second plane.
 21. The batteryof claim 18 wherein the battery is an alkali metal liquid cathodebattery.
 22. The battery of claim 18 wherein the battery comprises alithium thionyl chloride battery.
 23. The battery of claim 18 whereinthe battery comprises a lithium bromine chloride battery.
 24. Thebattery of claim 19 wherein the protective plate comprises insulativethermoplastic material.
 25. The battery of claim 18 wherein the fuse ismade of non-magnetic materials.